1. Technical Field
The present invention relates generally to gillnets or similar fishnets formed of multiple synthetic strands; and, more particularly, to improved multiple strand twisted fishnet twines and methods of forming such twines from synthetic materials wherein the composite twine consists of a plurality of "A" strands each formed of a monofilament of synthetic material and at least one "B" strand formed of a plurality of twisted filaments with the "A" strands and the at least one twisted "B" strand being twisted together to form a composite multiple strand twisted synthetic twine wherein all "A" and "B" strands are exposed along the outer surface of the composite multiple strand twisted twine over a substantial portion of their lengths. For example, the present invention finds particularly advantageous use in the Alaskan fisheries where governmental regulations require that gillnets formed of synthetic twines have a minimum of at least thirty (30) strands or filaments; but, wherein such multiple strand twines have heretofore commonly been formed of a plurality of equal diameter filaments and, consequently, the resulting nets do not possess the desired characteristics of transparency or invisibility which is a requisite characteristic of such nets. The present invention readily meets the 30 strand or 30-plus strand requirement of the Alaskan fisheries while, at the same time, providing a 30 or 30-plus strand twisted twine having a small number of relatively thick monofilaments or "A" strands--say, for example, monofilaments on the order of about 1.5 mil (0.0015") in thickness--which are twisted together with at least one twisted multiple filament "B" strand comprising a plurality of relatively fine small diameter synthetic fibers--say, for example, filaments on the order of about 210 deniers--which are first twisted together to form the multiple filament "B" strand and where the thus twisted "B" strand is then twisted together with a plurality of monofilament "A" strands to form the composite 30 or 30-plus filament twine used to form the gillnet. The arrangement is such that the twine produced and, therefore, the nets employing such twines, are characterized by their transparency--i.e., invisibility in water--elasticity, durability, and the ease and efficiency with which knots can be formed, as well as enhanced knot stability.
2. Background Art
A wide variety of gillnets and gillnet forming procedures and equipment are presently known and used extensively throughout the world, in many of which the nets are formed of synthetic materials such, for example, as nylon, polypropylene, polyethylene, and the like, and/or combinations of such polymeric synthetic materials. While governmental regulations vary from fishery to fishery as to the nature and construction of those gillnets which are considered legal for use, in the Alaskan fisheries such governmental regulations require that the synthetic twines used in such nets comprise at least 30 strands or filaments. Many approaches have heretofore been employed by net manufacturers to meet this 30 to 30-plus strand requirement while attempting to optimize strength, transparency (or twine invisibility), durability and like characteristics. For example, in U.S. Pat. No. 3,329,061-Momoi, the patentee describes a twine construction, and fishnets produced therewith, wherein the twine comprises seven (7) strands or yarns--viz., a centercore formed of 210 denier nylon filaments having an "S" (i.e., clockwise) twist; and, six (6) outer strands or yarns formed of 210 denier nylon filaments having a "Z" (i.e., counterclockwise) twist wrapped thereabout. A commercial variation of this patented construction has long been available from Momoi Fish Net Manufacturing Co., Ltd. of Hyogo-ken, Japan, employing a twisted centercore formed of 210 denier synthetic filaments about which are wrapped six (6) synthetic strands or monofilaments to form a 7-strand twine wherein one strand comprises a multiple filament coaxial centercore and the remaining six (6) relatively large diameter strands each comprise a monofilament wrapped about the centercore. While such centercore constructions do serve to meet the 30 or 30-plus strand minimum requirement of the Alaskan fisheries, they have not served to optimize the strength and transparency characteristics so important to the fishing industry as a whole.